Cellphones are 'possibly' carcinogenic

That is the conclusion issued yesterday by 31 experts following a week-long meeting in Lyon, France, convened by the World Health Organization's International Agency for Research on Cancer (IARC).

They concluded that there is "limited" evidence suggesting that mobile phones raise the risk of malignant brain tumours by 40 per cent, but only in heavy users who have made calls lasting 30 minutes per day for 10 years. There was also limited evidence of increased risk for a type of brain cancer called acoustic neuroma, but not for any other types of brain cancer.

"There is some evidence for increased risk of glioma and acoustic neuroma," says Kurt Straif, head of the IARC's monographs programme in a press conference yesterday. "But it is not clearly established that the use of mobile phones does cause cancer in humans."

Acoustic neuromas are relatively rare, with an incidence of one per 100,000 people. They account for about 6 to 10 per cent of all brain tumours worldwide. Gliomas are much more common, accounting for 60 per cent of all brain cancers in the US.

You decide

Asked what consumers should do in the light of the new findings, Straif said that texting and using of hands-free phones "lowers exposure by at least an order of magnitude", but that it is down to consumers to decide what precautionary measures they should take.

He added that governments, not the working group, should make recommendations on how to regulate mobile phones in the light of the findings.

Robert Baan, the senior IARC scientist in charge of publishing the findings, said that the conclusion of a "2B classification" for mobile phone radiation ranked it alongside 240 other possible carcinogens, including bathroom talcum powder, low-frequency electromagnetic radiation from power lines and a host of pesticides, herbicides, printing and dry-cleaning chemicals.

Jonathan Samet of the University of Southern California, Los Angeles, chairman of the working group, said that the key evidence for the classification came from two major international studies. The first, called Interphone, identified the higher risk of glioma in heavy users, but found otherwise that there was no risk of brain cancer in users from 13 countries between 1997 and 2004.

The second, led by Lennart Hardell at Örebro University in Sweden, found that the risk of acoustic neuromas quadrupled in users of analogue cellphones. These types of phones were phased out in 2000 in the UK and 2008 in the US.

Gaps and uncertainties

The search for a mechanism by which such low levels of radiation could cause cancer has failed so far, not least because the radiation is too weak to cause mutations by breaking bonds in DNA. "We have found threads of evidence of how cancer might occur, but there are gaps and uncertainties," said Samet.

Responding to criticisms made last week that the IARC had ignored important studies, Straif said that all available studies were included in the review. "Several of the latest analyses were made available to the IARC a week before the meeting," he says, adding that all national analyses from the Interphone study had been included too, as demanded by IARC's critics.

"This is the first scientific evaluation of all the literature on the subject of whether mobile phone radiation causes cancer," says Straif. "It brings it to a new level of consensus."

Samet admitted that there were problems even with the largest and most reliable studies, such as Interphone, because people find it hard to remember how often they have used their mobile phones in the past. Also, new, safer methods of mobile phone use such as texting and hands-free mean that we need updates on cancer risk. "The working group was struck by the need for further research to fill in all the gaps," he says.

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